Expert Witnesses- A View From The Bar

Sep 2020

This is a comment piece the Solicitors Journal Gazette asked me to write for publication in March 2020.

A barrister co-defending with me in a Crown Court trial pulled no punches when he began his cross-examination of an expert witness with this question;  “Are you going to apologise for your incompetence now or at the conclusion of your evidence?”.  The half-hour that followed was a master class in how to cross-examine an expert; it was also a master-class in how not to give expert evidence.

It might seem obvious that any expert should be a knowledgeable and impressive witness, but the truth is some experts are better than others. Every barrister has a tale about how they undid an expert in cross-examination, but in too many cases the experts are insufficiently knowledgeable– one police drugs expert recently admitted to me that she had not heard of a certain type of cannabis, but then when she checked police records she had to admit it was available in the UK .

There are also occasions when an expert is too amenable to suggestion.  It might be thought this is a result of the expert merely fulfilling their duty to assist the Court rather than provide unbending and partisan evidence, but a degree of robustness and firmness of thought is permissible.

So how to identify the best witness? Inquiries made with colleagues will usually identify the most appropriate and best expert. The Bar too is a very good sounding board, for most chambers will have dozens of barristers who are familiar with experts in their field of specialism and will have seen them in court. Notwithstanding Direct/Public Access, it’s still rare for criminal law barristers such as myself to instruct an expert witness, but we are frequently asked informally for advice, and will gladly provide it.  Identifying the best expert is one thing; securing their services, however, is another.

I was one of the prosecuting barristers in the trial of Ian Paterson, the surgeon who operated unnecessarily on patients and who was in the news recently following the report from the independent inquiry that was set up following his conviction.  In that case, there was a reluctance on the part of some medical experts to assist the prosecution. We shall never know the truth behind the reasons given for this reluctance, but it was possible to discern a feeling that heads were best kept below parapets, and that it was all too difficult, too time consuming and financially unwise.  To be fair, the rates payable by the Crown Prosecution Service to expert witnesses are not attractive, particularly in a case that might require a medical practitioner to be at court for weeks on end with all the inconvenience that causes to their practice.

The same is true of defence witnesses. We frequently encounter difficulties instructing defence experts, and only manage to do so after an unseemly haggle with the Legal Aid Authority. Even then we are often left with a disgruntled expert, which is far from ideal.

The Paterson case was very unusual – if not unique –  in that potential experts were faced with many imponderables, but it nonetheless highlights the importance of ensuring an expert understands what will be required of him or her. Clarity of instructions and scope of evidence should be a matter of course, but any expert should be informed of all other incidental burdens and inconveniences; some do not realise they may be called upon at short notice, or liaise with another expert, and have to wait at court for one or more days to give evidence.

Things are simpler, of course,  if money is not such a concern. However, instructing a good, able and willing expert, and briefing him or her fully will prevent calamites like the one in my recent case. At the end of his cross-examination, the defence barrister asked the expert if he had anything else to say. “Yes”, replied the expert, “I would like to apologise to the Court for my incompetence.”